In answer to your question, the problem I thought I had was Selespeed hydraulic issues and gear selection but because thet's what I thought the issue was everybody else did also; including the so called specialists!!!
The reality is that QSP made no assumptions, did a fresh diagnostic and told me the issue was not in fact the Selespeed unit but a sensor that would have cost me no more than a good night out?
In the end I had to replace the gearbox and selespeed unit because some monkey decided the only way to get the selespeed unit off was to bash the ******** out of it with a very heavy hammer rather than locate the holding bolt underneath and quarter turn it and heh presto. Because of his actions the internal selespeed rod had dropped into the box and jammed the gears, damaging both the gearbox and selespeed sensors with his bloody hammer!!!
Anyway, thanks again guys and remember the leason learned.